First application of a digital mirror Langmuir probe for real-time plasma diagnosis.

For the first time, a digital Mirror Langmuir Probe (MLP) has successfully sampled plasma temperature, ion saturation current, and floating potential together on a single probe tip in real time in a radio-frequency driven helicon linear plasma device. This is accomplished by feedback control of the bias sweep to ensure a good fit to I-V characteristics with a high frequency, high power digital amplifier, and field-programmable gate array controller. Measurements taken by the MLP were validated by a low speed I-V characteristic manually collected during static plasma conditions. Plasma fluctuations, induced by varying the axial magnetic field (f̃ = 10 Hz), were also successfully monitored with the MLP. Further refinement of the digital MLP pushes it toward a turn-key system that minimizes the time to deployment and lessens the learning curve, positioning the digital MLP as a capable diagnostic for the study of low radio-frequency plasma physics. These demonstrations bolster confidence in fielding such digital MLP diagnostics in magnetic confinement experiments with high spatial and adequate temporal resolution, such as edge plasma, scrape-off layer, and divertor probes.

Assessment of the response of indigenous microflora and inoculated Bacillus licheniformis endospores in reconstituted skim milk to microwave and conventional heating systems by flow cytometry.

Heat treatment is one of the most widely used processing technologies in the dairy industry. Its primary purpose is to destroy microorganisms, both pathogenic and spoilage, to ensure the product is safe and has a reasonable shelf life. In this study microwave volumetric heating (MVH) was compared with a conventional tubular heat exchanger (THE), in terms of the effects of each at a range of temperatures (75°C, 85°C, 95°C, 105°C, 115°C, and 125°C) on indigenous microflora viability and the germination of inoculated Bacillus licheniformis endospores in reconstituted skim milk. To assess the heat treatment-related effects on microbial viability, classical agar-based tests were applied to obtain the counts of 4 various microbiological groups including total bacterial, thermophilic bacterial, mesophilic aerobic bacterial endospore, and thermophilic aerobic bacterial endospore counts, and additional novel insights into cell permeability and spore germination profiles post-heat treatment were obtained using real-time flow cytometry (FC) methods. No significant differences in the plate counts of the indigenous microorganisms tested, the plate counts of the inoculated B. licheniformis, or the relative percentage of germinating endospores were observed between MVH- and THE-treated samples, at equal temperatures in the range specified above, indicating that both methods inactivated inoculated endospores to a similar degree (up to 70% as measured by FC and 5 log reduction as measured by plate counting for some treatments of inoculated endospores). Furthermore, increased cell permeability of indigenous microflora was observed by FC after MVH compared with THE treatment of uninoculated skim milk, which was reflected in lower total bacterial count at a treatment temperature of 105°C. This work demonstrates the utility of FC as a rapid method for assessing cell viability and spore inactivation for postthermal processing in dairy products and overall provides evidence that MVH is at least as effective at eliminating native microflora and inoculated B. licheniformis endospores as THE.

Peritonitis por Streptococcus pluranimalium, un patogéno poco habitual / Peritonitis caused by Streptococcus pluranimalium: an unusual pathogen

Streptococcus pluranimalium es una bacteria descrita como causante de infección en animales y su aislamiento es poco habitual en humanos. No se han descrito casos de peritonitis por esta bacteria, tampoco se han descrito infecciones por la misma en Panamá. Presentamos el caso de un masculino de 8 años con enfermedad renal crónica, en tratamiento con diálisis peritoneal, que ingresó por una descompensación de su balance hídrico. En liquido peritoneal presentó hallazgos compatibles con peritonitis y crecimiento de S.pluranimalium en los cultivos del mismo. El cuadro clínico se resolvió con 2 semanas de tratamiento con cefotaxima+ cefalotina inicialmente intravenosa y después peritoneal. El avance de las técnicas de identificación de bacterias permite describir nuevas especies como causantes de infección. Al haber pocos casos reportados es difícil establecer guías sobre la sensibilidad antibiótica. El S.pluranimalium es habitualmente sensible a aminoglucosidos, vancomicina y cefalosporinas.

Streptococcus pluranimalium is a bacteria described as a cause of infection in animals, and its isolation is unusual in humans. There have been no reported cases of peritonitis in humans by this bacteria and in fact no reported infections by this bacteria in Panama. We present the case of an 8 year old male with chronic renal disease, on treatment with peritoneal dialysis admitted to the hospital due to fluid imbalance. Peritoneal fluid analysis was compatible with peritonitis, and cultures grew S. pluranimalium. Clinical manifestations resolved after two weeks of treatment with cefotaxime and cefalotin. Advances in bacterial identification techniques have enabled the reporting of new species as causes of infection. Since there are few reported cases, it is difficult to establish guidelines for antibiotic treatment. The S. pluranimalium is usually sensitive to vancomycin, aminoglycosides and cephalosporins.

The digital mirror Langmuir probe: Field programmable gate array implementation of real-time Langmuir probe biasing.

High bandwidth, high spatial resolution measurements of electron temperature, density, and plasma potential are valuable for resolving turbulence in the boundary plasma of tokamaks. While conventional Langmuir probes can provide such measurements, either their temporal or spatial resolution is limited: the former by the sweep rate necessary for obtaining I-V characteristics and the latter by the need to use multiple electrodes, as is the case in triple and double probe configurations. The Mirror Langmuir Probe (MLP) bias technique overcomes these limitations by rapidly switching the voltage on a single electrode cycling between three bias states, each dynamically optimized for the local plasma conditions. The MLP system on Alcator C-Mod used analog circuitry to perform this function, measuring Te, VF, and Isat at 1.1 MSPS. Recently, a new prototype digital MLP controller has been implemented on a Red Pitaya Field Programmable Gate Array (FPGA) board which reproduces the functionality of the original controller and performs all data acquisition. There is also the potential to provide the plasma parameters externally for use with feedback control systems. The use of FPGA technology means the system is readily customizable at a fraction of the development time and implementation cost. A second Red Pitaya was used to test the MLP by simulating the current response of a physical probe using C-Mod experimental measurements. This project is available as a git repository to facilitate extensibility (e.g., real-time control outputs and more voltage states) and scalability through collaboration.

Subungual Melanoma of the Hand.

BACKGROUND: The diagnosis of subungual melanoma (SUM) can be challenging and SUMs generally have a worse prognosis than melanomas arising elsewhere. Due to their rarity, the evidence to guide management is limited. This study sought to identify clinicopathological features predictive of outcome and to provide guidelines for management. METHODS: From a large, single-institution database, 103 patients with in situ (n = 9) or invasive (n = 94) SUMs of the hand treated between 1953 and 2014 were identified and their features analyzed. RESULTS: The most common site of hand SUMs was the thumb (53%). Median tumor thickness was 3.1 mm, and SUMs were commonly of the acral subtype (57%), ulcerated (58%), amelanotic (32%), and had mitoses (73%). Twenty-one patients reported prior trauma to the tumor site. Twenty-two patients were stage III at diagnosis; 7 underwent therapeutic lymph node dissection and 22 underwent elective lymph node dissection (5 positive), while 36 had sentinel node biopsy (SNB), 28% of which were positive. Forty percent of SNB-positive patients had involved non-sentinel nodes (SNs) in their completion lymph node dissection. Five-year melanoma-specific survival (MSS) and disease-free survival (DFS) rates were 70% and 52%, respectively. On multivariate analysis, regional node metastasis and right-hand tumor location were significant predictors of shorter DFS and MSS, whereas mitoses negatively impacted DFS only and increasing Breslow thickness impacted MSS only. CONCLUSIONS: This study confirms that SUMs on the hand usually present at an advanced stage. Distal amputation appears safe for invasive SUMs, and SNB should be considered as these patients have a high risk of both SN and non-SN metastasis.

Síndrome de pseudo-Bartter como presentación inicial de fibrosis quística

Las manifestaciones clínicas de la fibrosis quística comprometen diferentes órganos; siendo los sistemas respiratorio y gastrointestinal los más frecuentemente afectados. Puede presentarse como un desequilibrio ácido-base y electrolítico conocido como síndrome de pseudo-Bartter que se define como un episodio de deshidratación con alcalosis metabólica hipoclorémica hiponatrémica e hipocalémica en ausencia de alteración tubular renal. Se presenta el caso clínico de un lactante menor masculino de cuatro meses con dos hospitalizaciones previas por deshidratación moderada y desequilibrio hidroelectrolítico con hiponatremia. La tercera hospitalización fue el 27 de enero de 2017 por 20 días. En esta ocasión fue admitido por gastroenteritis aguda, con deshidratación moderada, desequilibrio hidroelectrolítico, y observación por un trastorno metabólico. Por presentar deshidratación con alcalosis metabólica hipoclorémica hiponatrémica e hipocalémica sin tubulopatía renal se diagnosticó síndrome de pseudo Bartter y se sospechó fibrosis quística que se corroboró con medición de electrolitos en sudor y análisis molecular de las mutaciones . Conclusión: Debe considerarse el diagnóstico de fibrosis quística en un niño, sobre todo menor de dos años, con deshidratación, alcalosis metabólica hiponatrémica hipoclorémica aunque no haya presentado síntomas respiratorios o gastrointestinales típicos de la enfermedad. El diagnóstico temprano es fundamental para mejorar el pronóstico y la sobrevida a largo plazo

The clinical manifestations of cystic fibrosis may involve multiple organs. Although the respiratory and gastrointestinal are the most commonly affected systems, it can present as an acid- base and electrolyte imbalance called pseudo -Bartter syndrome which is defined as an episode of dehidration with metbolic alkalosis with hypochloremia, hyponatremia and hypokalemia in the absence of renal tubular pathology. We report a case of a 4-month-old male infant with 2 previous episodes of moderate dehydration and hydroelectrolyte imbalance with hyponatremia. He was admitted on January 27 th 2017 for 20-days hospital stay. On his 3th hospitalization, he was admitted with acute gastroenteritis, moderate dehydration, hydroelectrolyte imbalance, and probable metabolic disorder. Due to the presence of metabolic hypochloremic alkalosis with hyponatremia and hypokalemia without renal tubulopathy, Pseudo Bartter Syndrome was diagnosed and cystic fibrosis was suspected and corroborated later with the measurement of sweat electrolytes and molecular analysis of mutations. Conclusion: The diagnosis of cystic fibrosis must be suspected in a child, especially those under 2 years old, with hyponatremic hypochloremic,hypokalemic metabolic alkalosis dehydration should be considered even in the absence of respiratory or gastrointestinal symptoms, which are typically present in this disease. An early diagnosis is essential to improve the prognosis and long term survivor

Clorhidrorrea Congénita en lactante: Reporte de un caso

La Clorhidrorrea Congénita ( CC )es un trastorno autosómico recesivo raro, causado por un defecto en el intercambio de cloruro/bicarbonato en el íleon y colon y caracterizado por heces acuosas con concentraciones de Cl- alrededor de 150 meq /litro. Reportamos el caso de un niño de 1 año de edad con antecedente prenatal de polihidramnios y al nacimiento mal rotación intestinal, cambios de fórmulas por diarreas acuosas desde el cuarto mes de vida, pobre ganancia ponderal, deshidratación y alcalosis metabólica

Congenital chloride diarrhea (CCD) is a rare autosomal recessive condition, characterized by watery stools containing Cl- concentration around 150 mEq/liter. We report the case of a 1-year-old boy with prebirth history of polyhydramnios, intestinal malrotation, multiple formulas changes due to aqueous diarrhea since his fourth month of life, poor weight gain, dehydration and metabolic alkalosis

Radiation dose to workers due to the inhalation of dust during granite fabrication.

There has been very little research conducted to determine internal radiation doses resulting from worker exposure to ionising radiation in granite fabrication shops. To address this issue, we estimated the effective radiation dose of granite workers in US fabrication shops who were exposed to the maximum respirable dust and silica concentrations allowed under current US regulations, and also to concentrations reported in the literature. Radiation doses were calculated using standard methods developed by the International Commission on Radiological Protection. The calculated internal doses were very low, and below both US occupational standards (50 mSv yr(-1)) and limits applicable to the general public (1 mSv yr(-1)). Workers exposed to respirable granite dust concentrations at the US Occupational Safety and Health Administration (OSHA) respirable dust permissible exposure limit (PEL) of 5 mg m(-3) over a full year had an estimated radiation dose of 0.062 mSv yr(-1). Workers exposed to respirable granite dust concentrations at the OSHA silica PEL and at the American Conference of Governmental Industrial Hygienists Threshold Limit Value for a full year had expected radiation doses of 0.007 mSv yr(-1) and 0.002 mSv yr(-1), respectively. Using data from studies of respirable granite dust and silica concentrations measured in granite fabrication shops, we calculated median expected radiation doses that ranged from <0.001 to 0.101 mSv yr(-1).

Detection of unsuspected spinal cord compression in melanoma patients by 18F-fluorodeoxyglucose-positron emission tomography.

AIM: Positron emission tomography (PET) using (18)F-fluorodeoxyglucose can detect early or small metastatic deposits of melanoma and guide subsequent correlative anatomical imaging and treatment. The aim of this study was to assess the value of PET in demonstrating spinal cord compression by otherwise unsuspected metastatic disease. METHODS: Reports of 1365 PET studies performed on patients with melanoma were reviewed. Fifty patients considered to be at risk of spinal cord compression on the basis of PET were identified and 35 patients were analysed. Magnetic resonance imaging and computed tomography were used to confirm or refute the diagnosis. The symptoms and signs at the time of PET and follow-up status were compared between patients with and without confirmed spinal cord compression. RESULTS: In nine patients (26%) compression of the spinal cord or adjacent neurological structures was confirmed and eight of these patients had immediate treatment. Survival was poor in both patient groups, but three patients with confirmed compression maintained good neurological functional status following treatment. CONCLUSION: PET can detect imminent, unsuspected spinal cord compression in patients with metastatic melanoma. Immediate anatomical imaging of the spine is recommended in patients who have evidence of spinal cord compression on PET.

Sentinel node biopsy provides more accurate staging than elective lymph node dissection in patients with cutaneous melanoma.

BACKGROUND: In most major melanoma treatment centers, sentinel node biopsy (SNB), with complete regional lymph node dissection when a positive sentinel node is found, has now replaced elective lymph node dissection (ELND) for patients with primary cutaneous melanomas who are considered to be at moderate to high risk of nodal recurrence. As for ELND, however, no overall survival benefit for the SNB procedure has yet been demonstrated. The objective of this study was to compare the nodal staging accuracy and duration of survival for SNB and ELND. METHODS: A retrospective cohort study was conducted among patients with American Joint Committee on Cancer (AJCC) stage II disease treated at a single center between 1983 and 2000 with either SNB (n = 672) or ELND (n = 793). Multivariate analyses were performed using the logistic regression model for nodal staging accuracy and Cox's proportional hazards regression model for survival. RESULTS: Patient factors that influenced nodal positivity included age, Breslow thickness, ulceration, head or neck primary, and operation type (SNB or ELND). SNB was superior to ELND in the detection of micrometastases (odds ratio 1.23, 95% CI, 1.06 - 1.43) but operation type did not influence survival (P =.24). CONCLUSIONS: Sentinel node biopsy identified more nodal micrometastases than ELND but did not influence survival, although complete regional node dissection was performed in all patients who were SNB positive. This increase in staging accuracy likely results from the reliable identification of the appropriate lymph node field by preoperative lymphoscintigraphy, along with more detailed pathologic examination of the nodes removed by SNB.

Determinants of outcome in melanoma patients with cerebral metastases.

PURPOSE: To analyze prognostic factors, effects of treatment, and survival for patients with cerebral metastases from melanoma. PATIENTS AND METHODS: All melanoma patients with cerebral metastases treated at the Sydney Melanoma Unit between 1952 and 2000 were identified. From 1985 to 2000, patients were diagnosed and treated using consistent modern techniques and this cohort was analyzed in detail. Multivariate analysis of prognostic factors for survival was performed. RESULTS: A total of 1137 patients with cerebral metastases were identified; 686 were treated between 1985 and 2000. For these 686 patients, the median time from primary diagnosis to cerebral metastasis was 3.1 years (range, 0 to 41 years). A total of 646 patients (94%) have died as a result of melanoma. The median survival from the time of diagnosis of cerebral metastasis was 4.1 months (range, 0 to 17.2 years). Treatment was as follows: surgery and postoperative radiotherapy, 158 patients; surgery alone, 47 patients; radiotherapy alone, 236 patients; and supportive care alone, 210 patients. Median survival according to treatment received for these four groups was 8.9, 8.7, 3.4, and 2.1 months, respectively; the differences between surgery and nonsurgery groups were statistically significant. On multivariate analysis, significant factors associated with improved survival were surgical treatment (P <.0001), no concurrent extracerebral metastases (P <.0001), younger age (P =.0007), and longer disease-free interval (P =.036). Prognostic factors analysis confirmed the important influence of patient selection on treatment received. CONCLUSION: This large series documents the characteristics of patients who developed cerebral metastases from melanoma. Median survival was dependent on treatment, which in turn was dependent on patient selection.

Short-term digital surface microscopic monitoring of atypical or changing melanocytic lesions.

OBJECTIVE: To examine the outcome of short-term digital surface microscopic monitoring of suspicious or changing atypical melanocytic lesions. DESIGN: Digital surface microscopic (oil epiluminescence microscopy, and dermoscopy) images of clinically melanocytic lesions were taken with a color calibrated 3 CCD video instrument. In general, lesions were moderately atypical, flat or only slightly raised, without a history of change or surface microscopic evidence of melanoma, or were mildly atypical lesions with a history of change. Lesions were monitored during a 2.5- to 4.5-month period (median, 3.0 months). With the exception of overall change in pigmentation consistent with that seen in surrounding skin (solar exposure changes), any morphologic change after monitoring was considered an indication to excise. SETTING: Sydney Melanoma Unit, Sydney, Australia (a referral center). PATIENTS: A consecutive sample of 318 lesions from 245 patients (aged 4-81 years). MAIN OUTCOME MEASURE: Specificity for the diagnosis of melanoma. RESULTS: Of the 318 lesions, 81% remained unchanged. Of the 61 lesions that showed morphologic changes, 7 (11% of changed and 2% of total lesions) were found to be early melanoma (5 in situ and 2 invasive with a Breslow thickness of 0.25 mm and 0.28 mm, respectively). None of these melanomas developed any classic surface microscopic features of melanoma and therefore could be identified only by morphologic change. The specificity for the diagnosis of melanoma by means of short-term digital monitoring was 83%. CONCLUSION: On the assumption that all melanoma will change during the monitored period, surface microscopy digital monitoring is a useful adjunct for the management of melanocytic lesions.

Use of FT-NIR transmission spectroscopy for the quantitative analysis of an active ingredient in a translucent pharmaceutical topical gel formulation.

The objective of this study was to demonstrate the use of transmission Fourier transform near-infrared (FT-NIR) spectroscopy for quantitative analysis of an active ingredient in a translucent gel formulation. Gels were prepared using Carbopol 980 with 0%, 1%, 2%, 4%, 6%, and 8% ketoprofen and analyzed with an FT-NIR spectrophotometer operated in the transmission mode. The correlation coefficient of the calibration was 0.9996, and the root mean squared error of calibration was 0.0775%. The percent relative standard deviation for multiple measurements was 0.10%. The results prove that FT-NIR can be a good alternative to other, more time-consuming means of analysis for these types of formulations.

Do nodal metastases from cutaneous melanoma of the head and neck follow a clinically predictable pattern?

BACKGROUND: Potential lymphatic drainage patterns from cutaneous melanomas of the head and neck are said to be variable and frequently unpredictable. The aim of this article is to correlate the anatomic distribution of pathologically involved lymph nodes with primary melanoma sites and to compare these findings with clinically predicted patterns of metastatic spread. METHODS: A prospectively documented series of 169 patients with pathologically proven metastatic melanoma was reviewed by analyzing the clinical, operative, and pathologic records. Clinically, it was predicted that melanomas of the anterior scalp, forehead, and face could metastasize to the parotid and neck levels I-III; the coronal scalp, ear, and neck to the parotid and levels I-V; the posterior scalp to occipital nodes and levels II-V; and the lower neck to levels III-V. Minimum follow up was 2 years. RESULTS: There were 141 therapeutic (97 comprehensive, 44 selective) and 28 elective lymphadenectomies (4 comprehensive dissections, 21 selective neck dissections, and 3 cases in which parotidectomy alone was performed). Overall, there were 112 parotidectomies, 44 of which were therapeutic and 68 elective. Pathologically positive nodes involved clinically predicted nodal groups in 156 of 169 cases (92.3%). The incidence of postauricular node involvement was only 1.5% (3 cases). No patient was initially seen with contralateral metastatic disease; however, 5 patients (2.9%) failed in the contralateral neck after therapeutic dissection. In 68% of patients, metastatic disease involved the nearest nodal group, and in 59% only a single node was involved. CONCLUSIONS: Cutaneous malignant melanomas of the head and neck metastasized to clinically predicted nodal groups in 92% of patients in this series. Postauricular and contralateral metastatic node involvement was uncommon.

Predictors of left ventricular function after acute myocardial infarction: effects of time to treatment, patency, and body mass index: the GUSTO-I angiographic experience.

BACKGROUND: Despite the significant survival benefit associated with successful reperfusion therapy for acute myocardial infarction, global indices of outcome left ventricular function, such as ejection fraction, have often demonstrated little or no improvement. Although these measurements are confounded by numerous clinical, physiologic, and angiographic variables, no comprehensive analysis of this issue in a large series of patients is available. We used the Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries (GUSTO-I) database to better understand this phenomenon by determining independent predictors of left ventricular function and their interplay with regard to outcome ventricular function and improvement in function during the initial postinfarction week. METHODS: Ninety-minute and 5- to 7-day posttreatment global and regional indices derived from left ventriculograms were analyzed from a population of 676 patients. These observations were combined with clinical data to describe independent determinants of ventricular function outcome. RESULTS: Clinical factors predictive of global and regional ventricular function as well as improvement in function between 90 minutes and 5 to 7 days included time to treatment, early infarct-related artery flow grade, and body mass index. These same factors contribute significantly to compensatory hyperkinesis of the noninfarct zone, which is critical to maintenance of global ventricular function during this time period. CONCLUSIONS: The ventricular function benefits of early complete reperfusion after myocardial infarction are readily demonstrable after adjustment for multiple covariables and include (1) maintenance of global ventricular function and (2) prevention or delay in ventricular dilatation.

Differential response to targeted recruitment strategies to fitness promotion research by African-American women of varying body mass index.

OBJECTIVE: To assess patterns of recruitment into a community-based NCI-funded physical activity and dietary lifestyle change program targeting African-American women. DESIGN: Acquisition of a convenience sample to be screened for participation in a randomized, controlled prevention intervention. SETTING: African-American-owned and -operated health club located in an area of Los Angeles in which African Americans are concentrated. PARTICIPANTS: 893 African-American women. RECRUITMENT STRATEGIES: Social networking/word-of-mouth, staff presentations, mass and targeted media, and physician referral. MAIN OUTCOME MEASURE: Completion of screening questionnaire indicating a desire to enroll in the study. Screening questionnaire domains included self-reported height and weight, recent participation in organized weight loss programs, ability to walk one mile unassisted, current medication use, smoking status, personal medical history of cancer, sociodemographic variables, and recruitment source. RESULTS: Sociodemographic and anthropometric characteristics distinguished between respondents obtained through different recruitment strategies. In particular, women with a higher body mass index (BMI) were more likely than those with lower BMIs (P = .014) to be recruited through more personalized methods (eg, social networking). CONCLUSIONS: Culturally tailored recruitment strategies are critical in securing the participation of members of "hard-to-reach" populations, who are both under-represented in health promotion research and at high risk for chronic diseases.

Psychosocial versus nicotine-only self-report measures for predicting follow-up smoking status.

The most popular measure of tobacco dependence, the Fagerstrom Tolerance Questionnaire (FTQ), measures only tobacco-specific behaviors. In contrast, the most popular assessment of addiction among polydrug users is the Addiction Severity Index (ASI). Most of the subscales comprising the ASI are psychosocial measures, not drug-specific measures. A study was undertaken to compare the predictive utility of these two contrasting measures. The NAS (adapted from the FTQ) and the Addiction Severity Index (ASI) were used to predict future smoking status in a cohort of polydrug users followed annually for 3 years. The baseline NAS score explained more of the variance in Time 2 and Time 3 smoking status than did the ASI subscales. When previous smoking status was included as a covariate, however, the NAS no longer predicted future smoking status, whereas the ASI Subscales continued to explain significant variance in future smoking status. Results suggest that when past smoking behavior is known, a respondent's legal status and alcohol use may be more useful than a measure of tobacco dependence for predicting future smoking status.

Individual change amid stable smoking patterns in polydrug users over 3 years.

The pattern of stability/change in smoking status was examined annually in 254 community-dwelling polydrug users over 3 years. Respondents' smoking status was classified as nonsmoker, intermittent smoker, or "everyday" smoker. Results showed that the typical probability of retaining the same smoking status across any two consecutive assessments was: 0.77 for nonsmokers (never smokers and former smokers combined), 0.82 for everyday smokers, and 0.16 for intermittent smokers. The transition matrix proved stable across three observations; the predicted equilibrium distribution matched well with observed distributions. Fifty-five percent of intermittent smokers converted to everyday smoking within a year, but 29% converted to former-smoker status in the same period. No other transition exceeded 12%. Considerable flux in individual smoking status, particularly among intermittent smokers, was observed despite stable prevalence of smoking status in this population. Intermittent smoking status appeared to be a temporary "way station" between the two more stable everyday smoker and nonsmoker classifications. Results challenge current assumptions about "occasional" or "chipper" smokers.

Atovaquone suspension for treatment of Pneumocystis carinii pneumonia in HIV-infected patients.

OBJECTIVE: To describe clinical experience with atovaquone suspension for the treatment of Pneumocystis carinii pneumonia (PCP) in HIV-infected patients. DESIGN: A retrospective chart review. METHODS: The medical records of 54 HIV-infected patients with PCP treated with atovaquone were examined. The outcomes of 34 patients treated with atovaquone suspension (750 mg twice a day) were compared with those of 20 patients treated with atovaquone tablets (750 mg three times a day). RESULTS: The proportion of patients successfully treated was similar with the suspension (74%) and tablet (70%) formulations of atovaquone. The proportion of patients with an inadequate response to therapy was lower for patients treated with atovaquone suspension (15%) than tablets (30%). Both formulations were well tolerated. CONCLUSION: Atovaquone suspension is effective and well tolerated for the treatment of PCP.